Why did my Galaxy S4 mini suddenly stop working?

I put credit on my phone, and shortly after it powered off. I attempted to restart the device. The screen indicated that the phone was attempting an update, then powered off once more. After several minutes of leaving it off , 10 apprx, i attempted to restart the device without success. I then removed the battery, sim, and SD card and allowed it to lie dormant for an hour or so. After reassembling the phone, i once again attempted to power on the device. It remained dark and lifeless. That is, until i began sequencing between the power, home, and volume keys in a desperate effort. Shockingly, the phone screen illuminated, notating that i had options for an android OS update. It proclaimed that volume up indicates a confirmation and approval to update the OS system which notated that it could damage the phone or applications. The other option was volume down, cancelling the update. Not wanting to further damage the device, decided to cancel the update, which is supposed to be followed by an automatic restart of the device. The restart did not happen, leaving my phone lifeless. I have attempted sequencing the keys again to select the update; however, have been unsuccessful in my attempts. Would you have a logical explanation or remedy for this situation?